<template>
  <div>
    <!-- 无id时, 可以使用index(反正也是就地更新) -->
    <div
      v-for="(item, index) in arr"
      :key="index"
      style="display: inline-block"
    >
      <input v-model="flag" type="checkbox" :value="item" />
      <span>{{ item }}</span>
    </div>
    <p>你选中的元素, 累加的值和为:{{ sum }}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [9, 15, 19, 25, 29, 31, 48, 57, 62, 79, 87],
      flag: [],
    };
  },
  computed: {
    sum: {
      set(val) {
        console.log(val);
      },
      get() {
        return this.flag.length>0?this.flag.reduce((sum, next) => sum += next):0;
      },
    },
  },
};
</script>